|  | 1.1 | The OSI Reference Model and the Problems it Solves
| 1.1.1 | The layered network model: The OSI reference model
Network models use layers to simplify the networking functions. The separation of networking functions is called layering. To understand the importance of layering, let's consider the OSI reference model, a layered model for understanding and implementing computer communications. By using layers, the OSI reference model simplifies the tasks required for two computers to communicate with each other. Each layer can be focused on specific functions, thereby allowing the networking designer to choose the right networking devices and functions for the layer. In the OSI reference model, each of the seven numbered layers indicate distinct functions. The reasons for this division of network functions include the following: Layers divide the aspects of network operation into less complex elements. Layers define standard interfaces for plug-and-play compatibility. Layers enable engineers to specialize design and development efforts on modular functions. Layers promote symmetry in the different network modular functions so that they work together. Layers prevent changes in one area from affecting other areas, so each area can evolve more quickly. Layers divide the complexity of networking into separate, easy to learn operations.
| Web Links
| Cisco Connection Online
| Cisco Documentation
| Search Cisco